I am always on the look-out for books for our office-library. We have shelves that wrap around the office. Though we have filled it with lots of books, there are still empty spaces. I have checked out Goodwill, and other thrift stores, but they are just too pricey for my taste, even for used books!
Look at this garden book I got today for .50!
It was $30.00 book!
Another option for used books is the Library! I got a whole set of black/hard covered TimeLife books. They are all on different locations around the US. But the best part is that they are black. The librarian even bargained with my on the price! Oh yeah!